Resent-Date: Sun, 18 Jul 1999 19:27:29 +0200 (MET DST) Date: Sun, 18 Jul 1999 19:25:59 +0200 (MET DST) From: Roman Zippel X-Sender: zippel@zeus To: Linux/m68k Subject: signal bug fix Resent-From: linux-m68k@phil.uni-sb.de Hi, Below you can find the tested versions of the signal bug fix for 2.0 and 2.2/3. If you want to see the bug yourself, you can try the small program below if you don't believe me :). After some time it will either be killed by a SIGILL or a SIGSEGV (in the second case the program will print lots of '!'). I included also some optimizations for the 2.2 version, if we keep the return code nicely aligned, we need only to flush 1 cache line. I think the same can be done for the 030, but I currently have no 030 manual here, so I kept those two lines in. Jes, if you don't want to include that into 2.2, the significant changes are at line 478 and 797. bye, Roman #include #include #include #include void timer_handler(int sig) { } void buserr_handler(int sig, int code, struct sigcontext *sc) { static int oldaddr = 0; if (!oldaddr) oldaddr = sc->sc_pc; else if (oldaddr != sc->sc_pc) write(1,"!",1); } int main() { struct itimerval timer; struct sigaction sig; sigemptyset(&sig.sa_mask); sig.sa_flags = SA_NODEFER; sig.sa_handler = timer_handler; sigaction(SIGALRM, &sig, NULL); sig.sa_handler = buserr_handler; sigaction(SIGSEGV, &sig, NULL); timer.it_interval.tv_sec = 0; timer.it_interval.tv_usec = 10000; timer.it_value.tv_sec = 0; timer.it_value.tv_usec = 10000; setitimer(ITIMER_REAL, &timer, NULL); *(volatile int *)0; } --- linux-2.0/arch/m68k/kernel/signal.c.old Sun Jul 18 18:44:35 1999 +++ linux-2.0/arch/m68k/kernel/signal.c Sun Jul 18 18:46:45 1999 @@ -92,7 +92,7 @@ int fsize = 0; int formatvec = 0; unsigned long fp; - unsigned long usp = rdusp(); + unsigned long usp = rdusp() + 16; #if 0 printk("sys_sigreturn, usp=%08x\n", (unsigned) usp); @@ -236,8 +236,7 @@ * signum (parm #1) * sigcode (parm #2 ; vector number) * scp (parm #3 ; sigcontext pointer, pointer to #1 below) - * code1 (addaw #20,sp) ; pop parms and code off stack - * code2 (moveq #119,d0; trap #0) ; sigreturn syscall + * code (moveq #119,d0; trap #0) ; sigreturn syscall * #1| oldmask * | old usp * | d0 (first saved reg) @@ -297,10 +296,9 @@ put_user(regs->vector, tframe); tframe++; /* "scp" parameter. points to sigcontext */ - put_user((ulong)(frame+6), tframe); tframe++; + put_user((ulong)(frame+5), tframe); tframe++; /* set up the return code... */ - put_user(0xdefc0014,tframe); tframe++; /* addaw #20,sp */ put_user(0x70774e40,tframe); tframe++; /* moveq #119,d0; trap #0 */ /* Flush caches so the instructions will be correctly executed. (MA) */ --- linux-2.2/arch/m68k/kernel/signal.c.old Tue Jan 26 22:35:14 1999 +++ linux-2.2/arch/m68k/kernel/signal.c Sun Jul 18 01:01:50 1999 @@ -156,6 +156,9 @@ /* * Do a signal return; undo the signal stack. + * + * Keep the return code on the stack quadword aligned! + * That makes the cache flush below easier. */ struct sigframe @@ -175,9 +178,9 @@ int sig; struct siginfo *pinfo; void *puc; + char retcode[8]; struct siginfo info; struct ucontext uc; - char retcode[8]; }; @@ -478,7 +481,7 @@ struct switch_stack *sw = (struct switch_stack *) &__unused; struct pt_regs *regs = (struct pt_regs *) (sw + 1); unsigned long usp = rdusp(); - struct sigframe *frame = (struct sigframe *)(usp - 24); + struct sigframe *frame = (struct sigframe *)(usp - 4); sigset_t set; int d0; @@ -677,25 +680,6 @@ "cpushl %%bc,(%0)\n\t" ".chip 68k" : : "a" (temp)); - if (((vaddr + 8) ^ vaddr) & ~15) { - if (((vaddr + 8) ^ vaddr) & PAGE_MASK) - __asm__ __volatile__ (".chip 68040\n\t" - "nop\n\t" - "ptestr (%1)\n\t" - "movec %%mmusr,%0\n\t" - ".chip 68k" - : "=r" (temp) - : "a" (vaddr + 8)); - - temp &= PAGE_MASK; - temp |= (vaddr + 8) & ~PAGE_MASK; - - __asm__ __volatile__ (".chip 68040\n\t" - "nop\n\t" - "cpushl %%bc,(%0)\n\t" - ".chip 68k" - : : "a" (temp)); - } } else if (CPU_IS_060) { unsigned long temp; @@ -708,18 +692,6 @@ "cpushl %%bc,(%0)\n\t" ".chip 68k" : : "a" (temp)); - if (((vaddr + 8) ^ vaddr) & ~15) { - if (((vaddr + 8) ^ vaddr) & PAGE_MASK) - __asm__ __volatile__ (".chip 68060\n\t" - "plpar (%0)\n\t" - ".chip 68k" - : "=a" (temp) - : "0" (vaddr + 8)); - __asm__ __volatile__ (".chip 68060\n\t" - "cpushl %%bc,(%0)\n\t" - ".chip 68k" - : : "a" (temp)); - } } else { /* @@ -797,11 +769,9 @@ /* Set up to return from userspace. */ err |= __put_user(frame->retcode, &frame->pretcode); - /* addaw #20,sp */ - err |= __put_user(0xdefc0014, (long *)(frame->retcode + 0)); /* moveq #,d0; trap #0 */ err |= __put_user(0x70004e40 + (__NR_sigreturn << 16), - (long *)(frame->retcode + 4)); + (long *)(frame->retcode)); if (err) goto give_sigsegv; @@ -881,10 +851,10 @@ /* Set up to return from userspace. */ err |= __put_user(frame->retcode, &frame->pretcode); - /* movel #,d0; trap #0 */ - err |= __put_user(0x203c, (short *)(frame->retcode + 0)); - err |= __put_user(__NR_rt_sigreturn, (long *)(frame->retcode + 2)); - err |= __put_user(0x4e40, (short *)(frame->retcode + 6)); + /* moveq #,d0; notb d0; trap #0 */ + err |= __put_user(0x70004600 + ((__NR_rt_sigreturn ^ 0xff) << 16), + (long *)(frame->retcode + 0)); + err |= __put_user(0x4e40, (short *)(frame->retcode + 4)); if (err) goto give_sigsegv;